Add transformer support to Converters.

sdk/lib/convert/byte_conversion.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.convert;
 
 /**
  * The [ByteConversionSink] provides an interface for converters to
  * efficiently transmit byte data.
  *
  * Instead of limiting the interface to one non-chunked list of bytes it
  * accepts its input in chunks (themselves being lists of bytes).
  */
 abstract class ByteConversionSink extends ChunkedConversionSink<List<int>> {
   ByteConversionSink();
   factory ByteConversionSink.withCallback(void callback(List<int> accumulated))
       = _ByteCallbackSink;
   factory ByteConversionSink.from(ChunkedConversionSink<List<int>> sink)
       = _ByteAdapterSink;
 
   /**
    * Adds the next [chunk] to `this`.
    *
    * Adds the bytes defined by [start] and [end]-exclusive to `this`.
    *
    * If [isLast] is `true` closes `this`.
    *
-   * The given [chunk] is not held onto. Once the method returns, it is safe to
-   * overwrite the data in it.
+   * Contrary to `add` the given [chunk] must not be held onto. Once the method
+   * returns, it is safe to overwrite the data in it.
    */
   void addSlice(List<int> chunk, int start, int end, bool isLast);
 
   // TODO(floitsch): add more methods:
   // - iterateBytes.
 }
 
 /**
  * This class provides a base-class for converters that need to accept byte
  * inputs.
  */
 abstract class ByteConversionSinkBase extends ByteConversionSink {
 
   void add(List<int> chunk);
   void close();
 
   void addSlice(List<int> chunk, int start, int end, bool isLast) {
-    if (start != 0 || end != chunk.length) {
-      add(chunk.sublist(start, end));
-    } else {
-      add(chunk);
-    }
+    add(chunk.sublist(start, end));
     if (isLast) close();
   }
 }
 
 /**
  * This class adapts a simple [ChunkedConversionSink] to a [ByteConversionSink].
  *
  * All additional methods of the [ByteConversionSink] (compared to the
  * ChunkedConversionSink) are redirected to the `add` method.
  */
@@ skipping 47 matching lines @@
     v |= v >> 8;
     v |= v >> 16;
     v++;
     return v;
   }
 
   void close() {
     _callback(_buffer.sublist(0, _bufferIndex));
   }
 }